That's what the assault troop is for. If a cavalry organization needs infantry, they can be bolted on on a platoon basis. Dismounts for recces, OPs, security, etc are internal to Cav vehicles. If we assume 1 dismount per car, in the current 4 car troop, you get 16-20 dismounts per squadron and the assault troop can be sent to assist that squadron if the task requires it.
In terms of manning the aslt tp, we're still gaming that out in the RCAC but I've seen a few COAs. Needless to say, a Cav light or medium Cav squadron will have plenty of begrudging ground pounders if the need comes up and from what I've seen of the training and PT regimen they're running the pilot assault troops through in Gagetown (at least on paper) they'll be just fine at carrying out those mobility/counter-mobility/enabling tasks.